Preclinical data from a BRMP laboratory (Varesio) demonstrated that M-CSF is capable of prolonging IL-2-induced activation of monocytes in vitro, an effect which is attributable to upregulation of M-CSF receptor c-fms on monocytes by IL-2. In this Phase I study, patients will receive a 24-hour continuous intravenous infusion of IL-2 (Chiron) as inpatients on days 0 and 7 of each treatment cycle, followed by subcutaneous M-CSF as outpatients on days 1-5 and 8-12. Endpoints include toxicity, tumor response, number of circulating monocytes, M-CSF and IL-2 pharmacokinetics, and c-fms expression on monocytes.